The present invention relates to a diagnostic apparatus for diagnosing a vehicle for presence of any abnormality based on the driving condition parameters of various portions of an engine system, which are input to an electronic control unit of the vehicle.
In recent years, a vehicle engine system has been controlled using an electronic control unit (ECU). Specifically, the ECU receives signals from sensors provided at various portions of the engine system, and performs an computation based on the thus received data to control the ignition timing, the fuel injection quantity or the like.
In such an electronic control system, a self-diagnostic function for detecting an abnormal part of the engine system and informing a driver or a mechanic of an abnormality is usually incorporated. Diagnostic results of the ECU is typically stored in an EEPROM which is a writable non-volatile memory as described in Japanese Patent Laid-Open No. 61-98639. Another means for storing the self-diagnostic results is aback-up RAM (random access memory), which is less expensive than the EEPROM, as described in Japanese Patent Laid-Open No. 3-31041. The back-up RAM is supplied with a maintaining current from a battery of the vehicle even when the power of the system is turned off, and the stored data is maintained. That is, the back-up RAM is used as if it were a non-volatile memory by maintaining the power supply to the RAM. The back-up RAM loses the contents when the battery is removed from the vehicle, as may occur when replacing the batteries.
For example, when a battery is replaced in the car examination and maintenance, the diagnostic data stored in the back-up RAM is lost. This raises a problem when a car examination party tries to inspect the diagnostic data or check whether or not the self-diagnostic function is normal.
A diagnostic apparatus as described in Japanese Patent Laid-Open No. 3-31041 has two lamps, a code display lamp for blinking a trouble code designating an abnormality detected by the diagnosis, and a warning lamp which is lighted when the back-up data is broken and the diagnosis is uncompleted. If a user knows that the diagnosis is uncompleted as indicated by the warning lamp, the user can complete the diagnosis by running the vehicle for the period or distance required for the system to complete the diagnosis.
The present invention has been achieved in the light of such demand, and it is an object of the invention to effect the display of the diagnostic results and an indication of whether or not the diagnosis has been completed using a single display device or an indicator.
The information displayed on a driving panel of the vehicle or near a driver""s seat includes the vehicle speed, engine speed, fuel amount, seat belt warning, door warning, rear window heater warning, and the parameters regarding the air conditioning, the car audio, and the car navigation. The meters and displays are too complicated for ordinary drivers. Accordingly, it is desired that the number of warning lamps near the driver""s seat be suppressed or decreased.
According to one aspect of the invention, a diagnostic apparatus to be mounted on a vehicle is provided for diagnosing the vehicle based on the driving condition parameters of the vehicle. The diagnostic apparatus comprises: a display for displaying the presence or absence of an abnormality based on the diagnostic results; a switch for switching the diagnostic apparatus into a notification mode in response to a predetermined operation state; and a display controller, responsive to being switched into the notification mode, for displaying on the display whether or not the diagnosis has been completed. The operation state refers to a state where a user has or has not performed a specific operation.
According to the invention, an indication of whether or not the diagnosis has not been completed can be displayed on a display device or an indicator for indicating the diagnostic results by switching the mode of the diagnostic apparatus into the notification mode in response to a predetermined operation state.
According to another aspect of the invention, in the above mentioned diagnostic apparatus, the display is a lamp provided near a driver""s seat of the vehicle, and the indication of whether or not the diagnosis has been completed can be effected by blinking the lamp.
According to another aspect of the invention, one lamp is used as the display to effect the display of the diagnostic results and the indication of whether or not the diagnosis has been completed.
According to further another aspect of the invention, the predetermined operation state is a state of an ignition switch.
According to one embodiment of the invention, the diagnostic apparatus is switched into the notification mode in accordance with the predetermined operation state of the ignition switch. The apparatus according to the invention can be built by programming a conventional apparatus without substantially changing a hardware.
Further, according to another aspect of the invention, the display controller indicates an undiagnosed portion by a blinking pattern of the lamp. Since the undiagnosed portion is indicated in the blinking pattern of the lamp, a driver or a mechanic can learn the undiagnosed portion and can take a measure correspondingly.
According to yet another embodiment of the invention, the notification mode is released by starting the engine. The releasing function can be incorporated into to the diagnostic apparatus by programming without requiring a separate releasing device.